Assessment of water security under climate change for the large watershed of Dorudzan Dam in southern Iran

Assessment of water security under climate change for the large watershed of Dorudzan Dam in southern Iran | Evaluation de la sécurité de l’eau en conditions de changement climatique pour le grand bassin versant du barrage de Dorudzan dans le Sud de l’Iran Evaluación de la seguridad del agua en el marco del cambio climático para la gran cuenca de la presa de Dorudzan en el sur del Irán 伊朗南部Dorudzan大坝大流域气候变化条件下水安全评估 Avaliação da segurança hídrica em condições de mudança climática para a grande bacia da Barragem de Dorudzan no sul do Irã

2020

‘Blue water’ is the portion of freshwater flowing through rivers and the subsurface (groundwater) that is available for human consumption. ‘Green water’ is the portion stored in the unsaturated soil and vegetation canopy that is available only indirectly. Security of blue and green water resources is assessed over the Dorudzan Dam watershed in southern Iran. Precipitation and temperature data from 22 models of the Coupled Model Intercomparison Project Phase 5 are transiently downscaled at five climatic stations under three Representative Concentration Pathway (RCP) scenarios. The Soil and Water Assessment Tool (SWAT) is used to simulate and quantify blue and green water components over the region at the present time and under climate-change conditions. Climate-change study indicates that precipitation decreases (13–17%) and temperature increases (1.7–3. 3 °C) under the three RCPs, leading to substantial dam-inflow reduction. Evapotranspiration will increase while soil-water content will decrease, further intensifying green-water scarcity and vulnerability. Water use from the Kor River is sustainable at present, but future climate change will raise some ecological hotspots. Groundwater exploitation is currently unsustainable in all aquifers of the study area and climate change will further decrease the available groundwater, leading to intensification of the water crisis. Assessment of inter-annual security under climate change indicates that maximum scarcities of green water and surface blue water occur during spring and summer, and subsurface blue water (groundwater) maxima occur throughout the year. Thus, climate change threatens the future security of water resources in this arid watershed, requiring different management strategies for sustainability.

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